1. Field of the Invention
The present invention relates to a caption display method of a DTV (Digital Television), in particular to a caption display method of a DTV which is capable of displaying a caption having a certain size and a font on an appropriate position of a picture having 16:9 picture ratio when the picture having 4:3 picture ratio or enlarged 16:9 picture ratio is displayed on a screen of the digital television having 16:9 picture ratio.
2. Description of the Prior Art
Recently, according to realization of a digital television a broadcast station sends out a digital broadcast program for digital broadcasting and a converted digital broadcast program which is converted from an analog broadcast program on the air, and a digital television receives the digital broadcast programs and displays them.
Broadcast data corresponding to the digital broadcast program broadcasted from the broadcast station comprises picture data and broadcast program information. When the broadcast program information comprises caption information related to caption data, a DTV displays appropriately the caption on a screen with the picture. Herein, the caption information means a caption descriptor.
FIG. 1 is a construction profile illustrating a general caption display apparatus. It comprises a MPEG demultiplexer 1 of a DTV for outputting information related to video data and a broadcast program, namely, a packet including a PMT (Program Mapping Table) and an EIT (Event Information Table) by being inputted a MPEG-2 transmission stream and demultiplexing it when the DTV receives the MPEG-2 transmission stream transmitted from the broadcast station, a PMT buffer 3 and an EIT buffer 5 for storing the PMT packet and EIT packet separately after being inputted, a processor 11 for outputting a caption request select signal and a screen control signal when there is a caption output request after being inputted the caption descriptor information included in the PMT and EIT stored in the PMT buffer 3 and EIT buffer 5, for receiving a user order signal from a user input unit (not shown) such as a remote controller etc., and for judging whether there is the caption output request in the user order signal, a user graphic storing unit 17 for making a user select more detailed caption menu by outputting GUI picture information by receiving the caption request select signal, a video parser 7 for receiving the video data outputted from the MPEG demultiplexer 1 and parsing it into user data and MPEG-2 data, a DTV caption reproducer 9 for outputting caption data by receiving the caption request select signal outputted from the user data and processor 11, a MPEG-2 video decoder 13 for outputting a program video by decoding the MPEG-2 data outputted from the video parser 7, a video synthesizer 15 for synthesizing the program video outputted from the MPEG video decoder 13 with the caption data outputted from the caption reproducer 9 in accordance with the GUI picture information outputted from the user graphic storing unit 17 and outputting a synthesized picture signal, and a video reproducer 19 for outputting the reproduced picture signal in order to reproduce the synthesized picture signal on the screen.
Herein, the user data means caption data (for example, English, French, German etc.).
As depicted in FIG. 2, a caption processing method in accordance with the conventional technology will now be described with the operation of the above-described general caption processing apparatus.
When the user inputs the user order signal to the DTV through the remote controller, the processor 11 judges whether the caption output request is set on the caption menu in accordance with the caption output request of the user order signal in ST1. When it is set, the processor 11 requests the user data to the video parser 7 through the caption reproducer 9 in ST2. The caption reproducer 9 is inputted the packet corresponding to the caption outputted from the video parser 7 in ST3, and the caption reproducer 9 releases the packet of the caption data, and outputs the caption data corresponding to the present select caption output request in ST4.
The caption reproducer 9 analyzes the outputted caption data, and finds out all information related to width, height, and color of the caption about place and a certain reference point of the caption displayed on the screen in ST5, displays a caption window on a designated position of the screen in accordance with the information in ST6, and displays the caption on the caption window in ST7.
As depicted in FIG. 3, the picture of the broadcast program broadcasted from the broadcast station has 4:3 picture ratio.
Accordingly, in order to display the picture of the broadcast program having 4:3 picture ratio on the screen of the DTV having 16:9 picture ratio, the picture of the broadcast program having the 4:3 picture ratio has to be compensated appropriately.
FIG. 4A illustrates the picture having 4:3 picture ratio on the screen of the DTV having 16:9 picture ratio. The screen of the DTV having 16:9 picture ratio displays the picture having 4:3 picture ratio by receiving signals M1, M2 added to wide screen panel signals for a wide screen.
However, in the caption display method in accordance with the conventional technology, when the caption descriptor is not included in the data transmitted from the broadcast station, because the caption to be displayed on the DTV having 16:9 picture ratio can not be compensated, the caption (CAP) displayed on the screen of the DTV is displayed toward one side.
FIG. 4B illustrates the picture having 4:3 picture ratio which is displayed on the screen having 16:9 picture ratio by removing the side screen panel signals M1, M2.
As well as the slant problem of the caption of FIG. 4A, in the caption display method in accordance with the conventional technology, when the caption descriptor is not included in the data transmitted from the broadcast station, because the caption to be displayed on the screen of the DTV having 16:9 picture ratio can not be compensated, the caption (CAP) displayed on the screen of the DTV is displayed toward one side.
An object of the present invention is to provide a caption display method of a digital television which is capable of displaying caption after compensating the position and font of a picture corresponding to the picture ratio of a receiver regardless of a picture ratio of a broadcast program transmitted from a broadcast station.
Another object of the present invention is to provide a caption display method of a digital television which is capable of displaying a caption having a certain size and a font on an appropriate position of a picture having 16:9 picture ratio when a picture having 4:3 picture ratio or a picture having 16:9 picture ratio enlarged from the picture having 4:3 picture ratio is displayed on a screen of a digital television having 16:9 picture ratio.
In order to achieve the above-mentioned and other objects, the caption display method of the digital television in accordance with the present invention for displaying a picture with a caption by receiving a picture transmission stream transmitted from a broadcast station on a screen of a DTV having a certain picture ratio comprises a judging process for judging whether a caption descriptor is included in program system information protocol transmitted with the picture transmission stream, an adjusting process for adjusting automatically font and/or position of a caption to be displayed with a picture of the received picture transmission stream in order to be displayed corresponding to the picture ratio of the screen in accordance with the information included in a caption descriptor when there is the caption descriptor, and a displaying process for displaying a caption having the adjusted font on the adjusted position with the picture.
In order to achieve the above-mentioned and other object, a caption display method of a digital television in accordance with the present invention for displaying a caption with a picture by receiving the picture having 4:3 picture ratio or having 16:9 picture ratio enlarged from 4:3 picture ratio or having 16:9 picture ratio converted from 4:3 picture ratio by adding side signals on both sides from a broadcast station on a screen of a DTV having 16:9 picture ratio comprises a judging process for judging whether a caption descriptor is included in program system information protocol transmitted with the picture transmission stream, an adjusting process for adjusting automatically font and/or position of a caption displayed with the picture of the received picture transmission stream, and a displaying process for displaying a caption having the adjusted font on the adjusted position with the picture.
These and other objects of the present application will become more readily apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.